1. Field of the Invention
The present invention relates to a switching power supply having a backup function.
2. Background Art
In Patent Document 1, there is disclosed a technique in which a tertiary winding 4b is newly provided for a high frequency transformer in a switching power supply, in which a backup power supply including a secondary battery 14, a charging circuit 3c, and a discharging circuit 3d is connected to the tertiary winding 4b, and in which the discharging circuit 3d is operated at the time of power failure to thereby enable the electric power of the secondary battery 14 to be supplied to a load via the tertiary winding 4b and a secondary winding 4c. By using the technique disclosed in Patent Document 1, it is possible to supply the electric power to the load at the time of power failure, so that an externally mounted UPS (Uninterruptible Power Supply) can be made unnecessary. Further, also when the primary side converter is in failure, it is possible to supply the electric power to the load.
Patent Document 1: Japanese Patent Publication (Kokai) No. 9-261958 A (1997)